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Discussion Starter #1
Running 5.0 with 24# injectors, E303 cam, j pipes and side pipes. New O2 sensors, cleaned the throttle body, new plugs, new cap & rotor, new wires. Engine surges when cold and will not idle until some temp gets in the engine, maybe 130 or 140. Then idles great at around 850 to 900 rpm.
Any suggestions on getting engine to idle when cold?

Thanks, Ron
 

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Ron,

Don't know if this will help, maybe worth taking a look at. I have an '89 GT, stock 5.0 and it did the same thing. Found out that the Idle Air By-pass plunger, (located on the throttle body), was gummed up with carbon. It seems this is a natural occurrance and with enough build-up, does not allow the solenoid to actuate the plunger inside of it. Purchased some Eletronic Spray cleaner,(CRC makes it I think), .....removed and disassembled the solenoid from the plunger. Sprayed inside and out a couple of times to remove the carbon as best I could. Then blew it out with some compressed air, and let sit for 20 minutes before re-assembly. Once placed back on the throttle body assemby, then started the car up and no more issues for over 2 years now.

Hope this helps,
Kevin
 

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Discussion Starter #4
Kevin,

Thanks for the input, I will try this tomorrow. Also I read post from last December that had some suggestions. It sounds like when you change the injectors and cam from stock that the stock computer has trouble adjusting.

Ron
 

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Rob's right, and should be about 4.5 volts or so with Wide Open Throttle. Per the specifications of Ford's EEC, I believe .97 is the max voltage at idle...I've got mine set to .94 volts just for a safety margin.
 

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If you have an adjustable fuel pressure regulator, take 2 or 3 pounds of base out (vacuum off) and see if it helps. I have 24s and a B303 in my 93 GT, and it will only idle cold with about 35 pounds of base fuel. Stock is 39.
 

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For a speed-density system, I think the new injectors should work better with a corresponding computer change for base injector constants. Cam may or might not cause issues, depending on the severity of the profile. Mild cams, headers, and intakes all contribute less severely, from what I've seen (but most of my direct experience is Chevy).

Surely there are some Ford computer tuning experts lurking here somewhere who could point you to a vendor or help you out?
Good luck,
Peter
 

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An E303 and 24 pound injectors wouldn't idle well under any circumstances in a speed density car without an aftermarket chip, so I'd assume he has a mass air car.
 

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Ford sell an "Idle Air Bypass Kit" for about 20 bucks. It installs between the throttle body and the IAB. You adjust idle via 2 small hex screws in the kit. Engines with cams etc. can sometimes require more air at idle than the IAB can normally supply. Worked for me, much smoother idle and no more surging - *additionally eliminated the whistle from the BBK throttle body.
 
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